Clinical undergraduates generally have the following problems during their radiology internship: short internship period, low motivation, teachers using traditional teaching mode, and insufficient hardware and software facilities for image reading. In this study, RadiAnt DICOM Viewer and case-based learning (CBL) model were applied in online practice teaching for clinical undergraduates in the radiology department, which achieved good results. The results showed that the clinical undergraduates had a pass rate of 91.18% (124/136) in the image reading quiz and a mean score of (85.71±10.99) in the in-class quiz, with a pass rate of 91.91% (125/136). The satisfaction survey showed that 84.56% (115/136) of the students were more satisfied with the application of RadiAnt DICOM Viewer in image reading teaching; 80.88% (110/136) of the students expressed more interest in radiology after this training course; 90.44% (123/136) of the students thought that online practice teaching of radiology is feasible.